Digital watermarking has been deployed as an effective way to encode and then later retrieve auxiliary data in multimedia content after it has been distributed. One advantage is that the encoded data persists within the host media signal, even in environments where the content has been transformed for distribution or re-distribution in different distribution channels, like networks, broadcast channels, digital to analog conversion and back again, ambient air transmission and capture, etc. When implemented in systems for content identification, measurement and management, it can operate in concert with other content identification technologies, and support a range of applications. The world is rapidly transforming from one of mostly linear, single channel modes of distribution, to a highly non-linear world of content distribution and re-distribution (e.g., viral distribution on networks, transcoding for many devices, formats, geographic regions and markets). In this non-linear world, the likelihood arises that content signals are encoded with digital watermarks two or more times from initial creation to distribution and possible re-distribution on various communication channels. Content fingerprints can be used to identify content through pattern matching and related content recognition methods as a supplement to encoded data. Nevertheless, the need for unique identification (unique serialization of content), encoding of information other than mere identification, and efficient and/or offline decoding (e.g., when pattern matching database is not available or can no longer scale) necessitate use of digital watermarking. Given the need for such encoding, and in some cases, multiple layers of encoding, there is a challenge of limitations on the capacity of the watermark data channel within a unit of content, as well as collisions among different watermarks. Barring fundamental change in communication theory, channel capacity is a finite resource for watermarking.
Orchestration of encoded content is required to thrive in resource constrained environments. Such orchestration may be accomplished through bi-directional communication, such as the case where a first watermark is detected, interpreted, communicated to a system for orchestrating previous encoding with subsequent encoding, and then re-encoded. Often times the opportunity to re-encode with knowledge and maintenance of prior watermarks is not possible.
Objects that adhere to a common set of rules can maximize utilization of a scarce resource. Examples of such objects include data packets communicated in computer networks, insects, game theory, etc.
An orchestrated watermark encoding strategy can address the challenges posed by limited data encoding capacity of a host signal by implementing rule based encoding. Such a strategy defines a signal, data-link and payload schemas. The payload is the representation of the encoded data in a host signal. The encoding strategy preferably should be extensible, to allow adaptation of the strategy to support new applications and encoding technologies.
One aspect of the invention is a method of digital watermark processing that implements an orchestrated watermark encoding strategy. This method receives a content signal and performs a watermark decoding on the content signal. From the watermark decoding, the method determines a watermark state of the content signal. It then evaluates a watermarking rule based on the watermark state to determine watermark encoding to apply to the content signal to comply with the watermarking rule. Finally, it performs the watermark encoding on the content signal to embed layer of digital watermark into the content signal.
This method is implemented in digital watermark processors that are implemented within the distribution path of content tracks, including audio, visual and audio visual works. Content follows a distribution path that is either linear or non-linear (via broadcast and computer network distribution, or a combination of both). Nodes in the distribution path form a network of watermark processors through which content flows. In a typical implementation, the processors include watermark decoders that identify a watermark state present in the received audio or visual signal and watermark encoders that embed a watermark layer that overwrites, partially overwrites or co-exists with one or more previously embedded watermark layers.
Further features will become apparent with reference to the following detailed description and accompanying drawings.